冬小麦根层土壤水量平衡的系统动力学模型

为获取冬小麦根系层水量转化情况，该文采用系统动力学的建模思想和Vensim软件构建了冬小麦一维逐日土壤水量平衡模型。模型将2m土层概化为十个串联的水箱，计算了灌溉降雨后的土壤水分下渗、土壤蒸发、作物蒸腾、毛管上升补给和水分重分配等物理过程。利用河北省石津灌区军齐干渠北二支一斗渠2007－2009年两季冬小麦的田间试验资料对模型进行了率定和验证，结果显示率定期和验证期的平均残差比例和分散均方根比例均在15%以内。三种极端条件测试和六种参数的敏感性测试以及与Hydrus-1模型的比较表明模型假定合理，没有发生结构性错误。对灌区两季冬小麦生育期的土壤水分转化进行模拟，结果表明降雨和灌溉是主要供水水源，毛管水上升量很小，底部渗漏较大，而土壤储水量变化很小。

Soil water balance model in root zone of winter wheat based on system dynamics

A system dynamics-based one-dimensional soil water balance model (SD-WBM) was developed to estimate water budget in root zone of winter wheat on daily basis with Vensim software. It was assumed that the 2m-soil was comprised of 10 series-wound soil reservoirs. The physical processes, such as infiltration, soil evaporation, plant root water uptake, capillary rise and water redistribution between two adjacent soil reservoirs, were calculated in the model. For validation and calibration, field experiments of winter wheat were conducted in Shijing Irrigation Scheme in Hebei Province during 2007-2009, and model-calculated soil water content of 10 soil-depth intervals from 0 to 200 cm were compared with measured water content. The results showed that mean residual ratio (MRR) and distribution root mean square ratio (DRMSR) were all less than 15% in the validation and calibration. Furthermore, assumptions in SD-WBM were proved to be reasonable, with no structural error occurring through tests under three kinds of extreme condition, such as sensitive tests of six kinds of parameters as well as comparisons with Hydrus-1d model. Simulating results of soil water budget during growing season of winter wheat indicated that precipitation and irrigation were dominant water supply with little capillary rise and large amount of percolation. And water storage changes little in the harvest day compared to that in the sowing day.